If you're intrigued by this SEP article I would recommend going through [1] and [2] together, since they are both grouped in similar order by schools of thought on sorites paradox. The former is a well edited collection of papers on each position, and the latter is Timothy Williamson's frequently persuasive critique of each. I'm generally disinterested in analytic philosophy of language, but find myself returning again and again to this discussion because it is a frequent analog to a vast set of related problems.

[1] https://www.amazon.com/Vagueness-Reader-Rosanna-Keefe/dp/026... [2] https://www.amazon.com/Vagueness-Problems-Philosophy-Timothy...

I wrote my senior thesis on this topic when I was completing my philosophy major. One of the best texts on the subject is "Vagueness" by Williamson.

It's an arcane but super interesting topic that actually has wide implications. It's also IMO one of the most thorny problems in contemporary philosophy.

edit: I'm currently busy but can come back later to answer questions if anyone is interested.

http://www.amazon.com/Vagueness-Problems-Philosophy-Timothy-...